Many resources accessible via communications networks such as the Internet are malicious. Organizations often employ blacklist and/or whitelist approaches to prevent access to malicious resources. For example, an organization may compile or access a list of resource identifiers that identify resources that are believed to be malicious. Such a list is often referred to as a blacklist. The organization may prevent its internal hosts (e.g., computing systems) from accessing such malicious resources by blocking resource requests that include or are directed to resource identifiers on the blacklist. In other words, the resources identified by the resource identifiers on the blacklist can be said to be blacklisted.
Similarly, an organization may compile or access a list of resource identifiers that identify resources that are believed to be benign (or not malicious). Such a list is often referred to as a whitelist. The organization may prevent its internal hosts from accessing any resources not on the whitelist by blocking resource requests that include or are directed to resource identifiers not on the whitelist. In other words, the resources identified by the resource identifiers on the whitelist can be said to be whitelisted.